Many computers or servers often include a RAID card, which has an ability to combine multiple disks into a disk array for the purposes of data redundancy and performance improvement. Data is distributed across the multiple disks according to the disk array arrangements of the RAID card, referred to as RAID levels. The simplest RAID level 1 includes one or more disks for storing data and an equal number of additional “mirror” disks for storing copies of the data written to the disks. Other RAID levels, identified as RAID levels 2, 3, 4 and 5, segment the data into portions for storage across the multiple disks.
Before shipment, a test is needed to check whether a preset RAID level is correctly set in the RAID card.